package dfs;

public class 岛屿数量 {

    public int numIslands(char[][] grid) {
        int m = grid.length;
        int n = grid[0].length;
        int res = 0;
        for (int i = 0; i < m; i++) {
            for (int j = 0; j < n; j++) {
                if (grid[i][j]=='1'){
                    dfs(grid,i,j);
                    res++;
                }
            }
        }
        return res;
    }
    private void dfs(char[][] grid, int i, int j) {
        if (i<0 || i>=grid.length || j<0 || j>=grid[0].length || grid[i][j]=='0')
            return;
        grid[i][j] = '0';
        dfs(grid,i+1,j);
        dfs(grid,i-1,j);
        dfs(grid,i,j+1);
        dfs(grid,i,j-1);
    }
}
